There are a number of situations in which it is desirable to permit access to locked space by a plurality of different persons, but provide security of that access by requiring two separate elements to open the locked space. This prevents access by someone who has found a lost key, for example. A room in which medical drugs or valuables are stored, may require such security of access. Furthermore, it may be desirable to require a recording of those having access and the time that it occurred.
In real estate operations, in order to permit a number of different sales persons to have access to various properties for sale, key safes are used. The key safe is securely attached to the property and has a locked space therein in which the access device to the property is stored. This access device may be a key or it may be a card key. When a small real estate office having few salespersons has exclusive sales rights to several properties, the problem is not very complicated. Such may be a real estate office with a limited number of locks and a limited number of salespersons. A small number of locks permits changing of the locks when a salesperson terminates with the office. However, such is inconvenient even with a small office.
Key safes historically have been of the common key type where all users have an identical key. An improved type of key safe is the two-element input type where many different keys, each associated with a unique number, must be used to gain access. The improved type has the additional advantage of allowing recording of access and remains secure even if keys are lost. However, with these systems, if salespersons terminate there is no means of excluding them from the system other than by requiring them to give up their keys or by changing locks.
It is conventional in modern real estate sales practice for a group of real estate offices to band together for multiple listing. The group of real estate offices creates a real estate board which manages the multiple listing arrangement. Multiple listing means that the salespersons of any office belonging to the board can have access to any of the properties listed by the board. The number of key safes then becomes large, and it becomes very inconvenient to physically go out and change the key safes. Thus, when one of the salespersons terminates, the security of the key safe system is compromised unless that salesperson surrenders his/her key. Also, with such multiple listing systems, one of the offices may withdraw to create a larger scale compromise of security. In such a case, none of the salespersons from the withdrawn office would be entitled to access to the multiple listed properties. In these situations, a larger number of locks would have to be changed.
Thus, there is need for a system by which key safes can be attached at property available for sale and the key safes can be updated with new access information without the need for anyone going to each key safe specifically for updating its locking system or each key safe being transported to the board for updating its locking system. Due to the complexity of the problem, the real estate key safe system is considered to be a preferred embodiment of the electronic lock system of this invention, but there are other locked spaces to which an electronic lock system is also applicable, to enhance their security and reduce the need for direct security attention to each lock. Once hardware and software have been created to permit such remote updating, other desirable features, such as the routine collection of property showing data, become possible.